\(\bullet \)  Log-normal estimation We use log-normal distribution [1]} to model the winning price distribution\(\mu , \sigma \)  are sample mean and variance, and the winning rate at bid \(b\)  is given by \(winrate(b) = \int ^b_{\infty } Pr(z) dz \) . \(Pr(z) \sim \text{logNorma}l(\mu , \sigma )\) .
The baselines for eCPM_cost evaluation are listed as follows.
